Spark plug



June 24, 1924. 1,498,984

O. F. TRAMPE SPARK PLUG Filed March 15 1920 Patented June 24, 1924. l

UNIT-ED s'njxrlzs OLIVER F. TRAMPE, 0F ST. LOUIS, MISSOURI.

SPARK PLUG.

Application ledHarch 15, 1920. Serial No. 365,777.

To all whom it may concern.:

Beit known that I, OLivnR F. TBAMPE, a citizen of the United States, and a resident of the city of St. Louis and State of Mis# souri, have invented a new and useful Improvement in Spark Plugs, of which the following is a specification.

This invention relates to spark plugs suitable for use in connection with the igniting systems of internal combustion engines by means of which |aspark is produced for igniting 'the combustible charge within the working cylinders o-f the engine.

One of the principal objects of the present invention is to simplify the construction of the spark plug and to reduce the cost of manufacturing the same. Another object is to render the production of the spark more certain. The invention consists principally in a spark plug having a stationary central electrode and a series of stationary outer electrodes, thel center electrode having` a plate attached -thereto provided with a series of lnotches for cooperation with the outerl electrodes. The invention further consists in the construction and combination of. parts hereinafter described and claimed.

lIn the accompanying drawing wherein like symbols refer to like parts wherever they occur,

Fig. 1 is a central vertical section through the:1 spark plug embodying my invention; an

Fig, 2 is an enlarged horizontal cross section on the line 2--2 in Fig. 1.

The present spark plug comprises an outer casing or shell 1 having a reduced lower shank portion 2 which is threaded to enable the spark plug to be screwed into the cylinder of an engine. A central electrode, which is'in the form of a tapered metallic rod 3, is positioned within a tapered bore of a cylindrical insulating plug 4 of porcelain or other suitable material. The insulating core is provided with an annular flange 5 which is seated on an annular shoulder 6 formed in the inner wall of the shell 1. The annular flangev 5- of the insulating core is clamped rigidly in position within the shell 1 bymeans of a threaded 'bushing or sleeve 7 that is threaded into the upper end of the casing 1 and whose beveled lower end bears against the corresponding beveled upper surface of a metal washer 8'. An asbestos washer 9 is arranged between the under side of the annular flange 5 of the insulating core and .the upper surface of the supporting shoulder 6 of the casingto prevent breaking of the porcelain core when the same is engaged by the bushing 7 The central bore of-the insulating core is provided with a lining of mica or other suitable material 10.- The central electrode 3 projects upwardly beyond the upper end of the insulating core and is provided with a jam nut 11, the tightening of which draws the tapered electrode tightly into the tapered bore and thus prevents the escape of gas. The upper end of the spark plug is provided with a capl 12 of porcelain or other suitable material which is sleeved on the upper end of the insulating core. The upper end of the central electrode 3 projects through the cap 12 and has a terminal or binding .screw 13 threaded thereon for connecting the usual wire of the igniting system to the central electrode. The wire is clamped between the under surfaces of thc nut 13 andthe upper surface of ametal washer 14. This washer is sleeved on the upper end ofthe central electrode and is supported on the upper surface of the porcelain Cap 12. The cap l2 surrounds the upper end of the central electrode and is held in position by the binding nut 13. An asbestoswasher or gasket 15 is arranged between the lower end of the cap 12 and the vupper surface .of the tubular nut 7 to cushion the upper end of the cap and to seal the joint,

The lower end portion of the central electrode projects below the lower end of the insulating core and has a reduced threaded portion 16on which is sleeved a circular metal plate 17. A nut 18 is threaded on the reduced end portion 16 of thc central electrodeaud bears against the plate 17, thus firmly clamping said plate against the shoulder formed by the reduced endportion of the central electrode. The peripheral edge of the circular plate 17 is provided with a series of equally spa-ced semicircular notches 19. The lower end of the casing 1 is provided with a circular series o f electrode pins 20 which are pressed into the casing and extend downwardly therefrom. The pins extend into the notches 19 and are arranged concentric therewith. 4This arrangement forms a semicircular spark gap between the electnode pin 20 andthe edge of the semicirculal notch 19 in the plate 20. The plate 20 is prevented from rotating on the reduced por- .tion of the central electrode, thereby maintaining a uniform width of spark gap between the edge of the notches 19 and the outer surface of the electrode pins 20, by means of a web or key portion 21, which projects from one side of the reduced portion 16 of the central electrode and fits into a slot formed in the plate 17. With the hereinbefore described arrangement, the upper end of the insulating plug is enclosed by the porcelain cap 12, and this cap, when broken, can be readily replaced at only slight expensepwhereas with the usual type of spark plug, the projecting portion of the insulating plug is unprotected and is liable to be broken, thereby necessitating replacement of the entire insulating core. The semicircular -notches 19 in the plate 17, which embrace the outer electrode pins 20 provide a greater area of exposed surface between the pins and their respective notches, thus enabling a larger and more intensified spark to be produced. The number of sparking points assures the production of a spark even though some of the electrode pins become fouled.

Obviously the hereinbefore described construction admits of considerable modification without departing from the invention. Therefore, I do not wish to be limited to the exact details scribed.

What I claim is:

1. A spark plug comprising a shell having an outer electrode projecting therefrom, an insulating core, a central electrode extending through said insulating core, and aplate secured to the lower end of said central electrode, said plate having an opening into which said outer electrode projects.

2. A spark plug comprising a. shell having an outer electrode pin projecting from its lower edge, an insulating core, a central electrode extending through said insulating core, a plate secured to the lower end of said central electrode, means for preventing the rotation of said plate with respect to said central electrode, said plate having a notch in its edge into which said outer electrode of construction shown and dej pin projects.

' 3. A spark plug comprising a shell l1av ing a series of electrode pins extending therefrom, an insulating core within said she-ll, a central electrode extending through said core, .a disk secured to the lower end of said central electrode, said disk having a series of notches formed in its outer end into which said electrode pins project.

Signedat St. Louis, Missouri, this 10th day of March, 1920. l

OLIVER F. TRAMPE. 

